Scientific Forecaster Discussion
fxus61 krlx 230220
Area forecast discussion
National Weather Service Charleston WV
1020 PM EDT sun Sep 22 2019
very warm for the last day of Summer with high pressure aloft
and at the surface. Cold front on Monday, followed by high
pressure mid week. Weak front Thursday.
Near term /through Monday/...
as of 1015 PM Sunday...
Minor temperature edits to the overnight lows this evening.
Lowered a degree or Tow in a few locations.
As of 725 PM Sunday...
Made some wholesale edits to the pops through Monday with the
timing of the front, but the end result is more of just an hour
or two delay to the start in southeastern Ohio and two potential
lines of showers, one with the front and one with the weak
trough axis aloft. No thunder in this update.
As of 230 PM Sunday...
Main topic of discussion for today will be the abnormally warm
afternoon temperatures. Ridging aloft and surface high pressure
parked over the Carolinas will support southwesterly flow and
warm air advection. Temperature readings over the past few hours
have already surpassed guidance, so adjusted today's Max
temperature up a few degrees. Dry air mixing down along
sufficient momentum Transfer will continue to drop dew points
by a few degrees this afternoon, resulting in relative
humidities falling towards the low 30 percent range.
The ridge breaks down for the first day of fall as an encroaching
trough and associated surface cold front interrupts the dry
weather pattern. Hi-res models have a line of weakening showers
on the doorsteps of southeast Ohio near 8 am, crossing into the
mountains by the afternoon. While instability is not absent
along the front, precip accompanying this feature will lack
distinctive thunderstorm qualities and will remain more in the
shower variety. Activity along the mountains taper down at the
conclusion of the near term period, with drier air filtering in
along the northwesterly flow in the wake of the frontal passage.
Short term /Monday night through Wednesday night/...
as of 210 PM Sunday...
Low level Post-fropa cloudiness should gradually erode from
west to east Monday night, with temps dropping faster late in
the night as drier near sfc air finally settles into the region.
Sfc high pressure center is prog to move east overhead during
the day Tuesday, with a rather flat cloud deck possible across
the eastern half of the County Warning Area...where some lingering moisture will
persist around the 850 mb layer. Max temps on Tuesday will likely
be the coolest of the week. High pressure then shifts east
Tuesday night, and especially Wednesday. This will result in a
gradual development of sswrly low level flow by Wednesday
morning. If the llvl flow is rather slow to develop, then a few
areas across the low lands may dip into the 40s for Wed night
lows, with scattered areas in the mountains likely falling into
the 30s, with isolated sheltered/microclimate driven locations
in the extreme NE County Warning Area flirting with the upper 20s.
Significant warming of the atmospheric column is likely on
Wednesday as high pressure shifts away from the area. Given dry
soils along with a dry profile, temps will likely rocket
upwards between mid and late morning...with afternoon highs
much warmer than tuesday's values.
Long term /Thursday through Sunday/...
as of 210 PM Sunday...
12z GFS and 00z European model (ecmwf) is a little more aggressive with pushing
a front into the County Warning Area on Thursday. Should this occur, the front
will likely stall along the mountains before shifting back
northward as a warm front. Another notable warming trend is then
likely for late in the work week, and especially over next
weekend, as some impressive mid level ridging is prog to
influence area weather across much of the southern and eastern
Continental U.S.. would not be surprised to be flirting with record highs
at times for late this week and into next weekend, especially
with mainly dry conditions persisting.
Aviation /02z Monday through Friday/...
as of 725 PM Sunday...
Should get enough increasing flows tonight to inhibit valley fog
as 925mb winds increase to 15kts in the mountains and 30kts over
the Ohio River by 12z Monday. Cold front comes through with a
wind shift of 30-50 degrees from southwest to more westerly,
and gusts 20-25kts at the surface. Showers likely and have this
in prevailing with no restrictions in terms of visibilities,
but ceilings come down to MVFR at 2-3kft with the front and in
its wake. Could be two separate lines of showers, one with the
front, and one with the upper level trough trailing the front.
No thunder in this issuance. Western terminals return to VFR as
clouds break near the end of the forecast period.
Forecast confidence and alternate scenarios through 00z Tuesday...
Forecast confidence: high.
Alternate scenarios: timing of showers with the cold front could
vary by an hour or two.
Experimental table of flight category objectively shows consistency
of weather forecast office forecast to available model information:
h = high: taf consistent with all models or all but one model.
M = medium: taf has varying level of consistency with models.
L = low: taf inconsistent with all models or all but one model.
Date Monday 09/23/19
UTC 1hrly 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1hrly 20 21 22 23 00 01 02 03 04 05 06 07
crw consistency h h h h h h h h h h h h
heights consistency h h h h h h h h h h h h
bkw consistency h h h h h h h h h h h h
ekn consistency h h h h M M l l l l l l
pkb consistency h h h h h h h h h h h h
ckb consistency h h h h h h h h h h h h
After 00z Tuesday...
IFR or worse along the mountains overnight Monday night, in
stratus and Ridgetop fog, in the wake of a weak cold front.